Revert "Make compiler/optimizing/ symbols hidden."

This reverts commit e2727154f25e0db9a5bb92af494d8e47b181dfcf.

Reason for revert: Breaks ASAN tests (ODR violation).
Bug: 142365358

Change-Id: I38103d74a1297256c81d90872b6902ff1e9ef7a4
diff --git a/compiler/optimizing/intrinsics.h b/compiler/optimizing/intrinsics.h
index a33ed8b..ab68cce 100644
--- a/compiler/optimizing/intrinsics.h
+++ b/compiler/optimizing/intrinsics.h
@@ -17,13 +17,12 @@
 #ifndef ART_COMPILER_OPTIMIZING_INTRINSICS_H_
 #define ART_COMPILER_OPTIMIZING_INTRINSICS_H_
 
-#include "base/macros.h"
 #include "code_generator.h"
 #include "nodes.h"
 #include "optimization.h"
 #include "parallel_move_resolver.h"
 
-namespace art HIDDEN {
+namespace art {
 
 class DexFile;